Fix charts tooltip

[noxhirsch]

Breaking change

Proposed change

The tooltip of charts had a lot of whitespace because of the white-space: pre-line; which is needed to break the the lines of text.
Since there's always a line break before the text, because of the code formatter, the only solution here was to hide the first line.
I also adjusted the margin a little bit to make that part prettier.
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• Dependency upgrade
• Bugfix (non-breaking change which fixes an issue)
• New feature (thank you!)
• Breaking change (fix/feature causing existing functionality to break)
• Code quality improvements to existing code or addition of tests

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• This PR fixes or closes issue: fixes #
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Checklist

• The code change is tested and works locally.
• There is no commented out code in this PR.
• Tests have been added to verify that the new code works.

If user exposed functionality or configuration variables are added/changed:

• Documentation added/updated for www.home-assistant.io